The present invention relates to water cooled nuclear reactors which operate in a pressurized condition. The present invention is applicable to pressurized water reactors (PWR) and to boiling water reactors (BWR) of either direct or indirect cycle types. The pressurizer may be integral with, or separate from, the pressure vessel of the reactor.
A problem with these types of water cooled nuclear reactors is that there are accident conditions, or failures of the pressure vessel, which result in a loss of primary water coolant from the primary water coolant circuit causing the reactor core to become uncovered and uncooled.
A further problem with these types of water cooled nuclear reactors especially for use in marine applications when installed in, and used to propel and/or to provide power for, a ship is that violent motions of the ship through the water can cause the reactor core to become uncovered and uncooled.